Holder for cutting tip of milling cutter machine

ABSTRACT

A carbide cutting tip is mounted in a separate cartridge which is removably secured in a rotary milling cutter head, so that break-down of the tip will not endanger damage to the cutter head but only the cartridge.

United States atent Lundstrom et al.

[ 51 May 30, 1972 HOLDER FOR CUTTING TIP OF MILLING CUTTER MACHINE HansPer Olof Lundstrom; Bernt Soren Liljekvist, both of Sandviken, SwedenSandvikens Jernverks Aktiebolag, Sandviken, Sweden Filed: July 30, 1970Appl. No.: 59,649

Inventors:

Assignee:

Foreign Application Priority Data Mar. 24, 1970 Sweden ..4011/70 U.S. Cl..299/93 Int. Cl

Field of Search .299/91-93 [56] References Cited UNlTED STATES PATENTS1,473,498 1 [/1923 Morgan ..299/93 X 2,811,343 10/1957 Brown ..299/913,429,617 2/1969 Lauber ..299/93 FORElGN PATENTS OR APPLlCATlONS 6,611,973 4/ l 967 Netherlands ..299/92 Primary ElraminerErnest R. PurserAttorney-Pierce, Scheffler & Parker [57] ABSTRACT A carbide cutting tipis mounted in a separate cartridge which is removably secured in arotary milling cutter head, so that break-down of the tip will notendanger damage to the cutter head but only the cartridge.

3 Claims, 4 Drawing Figures HOLDER FOR CU'ITING TIP OF MILLING CUTTERMACHINE The present invention relates to a rock drilling machine of thekind in which the drilling is performed by milling cutter heads whichrotate simultaneously around their own axis and around an axis remotetherefrom.

In machines of the aforesaid kind difficulties have been encountered inthat when the carbide tips used for the drilling break down the toolholder is subjected to contact with the rock material and thereby isdamaged.

According to the invention such damage is avoided by mounting thecarbide tip in a separate cartridge which cartridge, in turn, is mountedin a rear shank. The advantage of this is that only the cartridge willbe damaged should the insert break down.

The invention will now be described with greater particu larity and withreference to the accompanying drawing, wherein:

FIGS. 1 and 2 show side and plan views, respectively, of a holderassembly according to the invention;

FIG. 3 is a plan view of another embodiment of a holder according to theinvention; and

FIG. 4 is a section on the line 4-4 in FIG. 3.

The holder assembly shown in FIGS. 1 and 2 consists of a shank having atits fore end a shaped recess 11 in which is mounted a cartridge 12,carrying a cutting tip 13 of cemented carbide or some otherwear-resistant material. In the illustrated case the tip is fastened inthe cartridge by brazing but may alternatively be attached by mechanicalclamping. The rear part of the shank 10 is fastened in a matching recessin a rotary milling cutter which is not shown in the Figure. For thispurpose and as shown in the Figure the shank may have a conical shape.

Cartridge 12 is secured in the shank 10 by means of a screw 14, and issupported at three support surfaces identified at l5, l6 and 17. Thesupport surfaces 16 and 17 are plane recesses on pins 18 and 19 mountedin the shank. The surfaces 15, 16 and 17 are raised from surroundingsurface portions of the recess 11 and thereby are easier to keep cleanfrom dirt.

The holder assembly 10, I2 is mounted in the cutter in such a way thatthe edge 20 acts as a cutting edge and the pressure from the drilledrock is directed towards the surface 21. The cartridge 12 is fixedagainst the action of this pressure, the fore part resting on thesurface I5 and the rear part being wedged between surfaces 16 and 17.

The drilling machine is fed forwards under control in such a way thatthe tips do not cut out the whole volume of the drill hole but follow aspiral path having a higher pitch than the length of the tips, thusleaving uncut portions between the cut portions. In order to break theseuncut portions the tool holder is provided with a shoulder 30 which maybe coated with some hard material, for instance a hard weld.

The foremost part of the tip should protrude from the shank 10 at adistance A at least equal to the feed per tooth of the cutter. In thisway the most protruding part 22 of the shank is prevented from cominginto contact with the rock if the insert should break. Thus the damagecaused when the tip breaks and the holder comes in contact with the rockis limited to damage to the cartridge 12.

FIGS. 3 and 4 show another embodiment of the holder according to theinvention. The shank 50 has a T-shaped slot or recess 51 and thecartridge 52 has a corresponding projection 53 extending to the rear ofthe cartridge and joined to the main part of the cartridge through ashank portion 53. When assembled, these parts form a T-slot connectioncarrying the cartridge in which the tip 54 is secured. A pin 55 islocated in the shank above a rear projection 56 on the cartridge andserves to lock the cartridge in the shank.

The surfaces 60 and 61 of shank 50which oppose surfaces of the cartridgeon either side of shank 53diverge in a downward direction to establish asuitable wedge form, so that the cartridge is carried solely by itswedging action between 60 and 61, and is spaced from the bottom of therecess 51 by the space 62. The T-slot connection is oriented in the samedirection as the rotation of the cutter, so that the connection ispressed together by pressure on the cutting tip.

The surfaces 60 and 61 may, as is illustrated in the drawing, alsoconverge laterally in order to stabilize the cartridge sideways.

In the same sense as in the embodiment illustrated in FIGS. 1 and 2, thecartridge 52 should protrude from the shank a distance A at least equalto the feed per tooth.

We claim:

1. A tool holder assembly for a milling cutter for rock drilling, saidassembly comprising a shank adapted to be mounted in the cutter and aholder mounted in said shank, in which the connection between the holderand the shank comprises a T-slot connection converging in the generaldirection of the mutual contact surfaces, the T-component being wedgedin the slot component.

2. A tool holder assembly according to claim I in which the tongue andgroove connection is directed in such a way that it is tightened by theworking pressure on the holder.

3. A tool holder assembly as claimed in claim 1 in which the holderprotrudes from the shank a distance not less than the feed per tooth ofthe cutter.

1. A tool holder assembly for a milling cutter for rock drilling, saidassembly comprising a shank adapted to be mounted in the cutter and aholder mounted in said shank, in which the connection between the holderand the shank comprises a T-slot connection converging in the generaldirection of the mutual contact surfaces, the T-component being wedgedin the slot component.
 2. A tool holder assembly according to claim 1 inwhich the tongue and groove connection is directed in such a way that itis tightened by the working pressure on the holder.
 3. A tool holderassembly as claimed in claim 1 in which the holder protrudes from theshank a distance not less than the feed per tooth of the cutter.